Transition-to-turbine seal apparatus and transition-to-turbine seal junction of a gas turbine engine

FIELD OF INVENTION

The invention generally relates to a gas turbine engine, and more particularly to a seal component between a transition and a turbine of such engine.

BACKGROUND OF THE INVENTION

In gas turbine engines, air is compressed at an initial stage, then is heated in combustion chambers, and the hot gas so produced passes to a turbine that, driven by the hot gas, does work which may include rotating the air compressor.

In a typical industrial gas turbine engine a number of combustion chambers combust fuel and hot gas flowing from these combustion chambers is passed via respective transitions (also referred to by some in the field as ducts and tail tubes) to respective entrances of the turbine. More specifically, a plurality of combustion chambers commonly are arranged radially about a longitudinal axis of the gas turbine engine, and likewise radially arranged transitions comprise outlet ends that converge to form an annular inflow of hot gas to the turbine entrance. Each transition exit is joined by a number of seals each of which bridges a gap between a portion of the exit and one or more turbine components. The latter, in various designs, are identified as row <b>1</b> vane segments. Adjacent component growth variances due to thermal expansion, mechanical loads, and vibrational forces from combustion dynamics all affect design criteria and performance of such a seal, referred to herein as a transition-to-turbine seal. Maintenance of component temperatures below particular limits is also desired and this may affect design of the seal and adjacent components. Consequently, the design of such seals has presented a challenge resulting in various approaches that attempt to find a suitable balance between seal cost, reliability, durability, installation and repair ease, performance, and effect on adjacent components.

For example, U.S. Pat. No. 6,751,962, issued Jun. 22, 2004 to Kuwabara et al., provides inclined cooling fluid holes drilled in a tail tube seal in addition to conventionally existing cooling fluid holes. These cooling fluid holes exit into the hot gas path, and are stated to cool the hot gas side of a downstream groove of the seal due to film effect. This is stated to increase reliability and decrease wear. A different approach is taken to cool the transition side of the seal in U.S. Pat. No. 6,769,257, issued Aug. 3, 2004 to Kondo et al. In this patent are disclosed cooling medium and heating medium channels provided in the outlet structure of a transition. Various embodiments are described that are stated to reduce the temperature difference of a flange formed at the downstream end of the transition, which attaches to a sealing component connecting to the turbine. Finally, in U.S. Pat. No. 6,860,108, issued Mar. 1, 2005 to Soechting et al., a seal was directed to prevent the outer and inner shrouds of the turbine's first stationary blade (i.e., row <b>1</b> vane segment) from heat damage and wear. The seal comprised a downstream portion having an inclined surface (inclining outwardly from the hot gas path) so that the cross-sectional area defined within the seal increased from an upstream point to a downstream point. Also, outlets for ejecting cooling air were provided that were disposed to release cooling air at the downstream end of the seal. Further, bleed holes were provided toward an upstream end section of the seal, near a front corner of the seal in the hot gas path. The latter are stated to “cool the film” [sic] of the parallel (non-inclined, more upstream) and the inclined (more downstream) surfaces of the seal that are in the hot gas path.

Despite the respective features of these and other transition-to-turbine seals and temperature equilibrating approaches known in the art, there remains a need for an improved transition-to-turbine seal.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the drawings that show:

<figref idrefs="DRAWINGS">FIG. 1</figref> provides a schematic cross-sectional depiction of a prior art gas turbine engine.

<figref idrefs="DRAWINGS">FIG. 2</figref> provides a cross-sectional view of the junction of a transition with a front end of a turbine, showing seals in the junction.

<figref idrefs="DRAWINGS">FIG. 3A</figref> provides a perspective view of one embodiment of a seal in accordance with the present invention. <figref idrefs="DRAWINGS">FIG. 3B</figref> provides an enlarged view of the region of <figref idrefs="DRAWINGS">FIG. 3A</figref> enclosed by dashed lines. <figref idrefs="DRAWINGS">FIG. 3C</figref> provides a cross-sectional view of the seal along line C-C in <figref idrefs="DRAWINGS">FIG. 3B</figref>, in functional association with a downstream portion of a transition.

<figref idrefs="DRAWINGS">FIG. 4A</figref> provides an end perspective view of a seal in accordance with the present invention, showing a female ship lap at the end. <figref idrefs="DRAWINGS">FIG. 4B</figref> provides an end perspective view of a seal in accordance with the present invention, showing a male ship lap at the end for mating engagement with the female ship lap shown in <figref idrefs="DRAWINGS">FIG. 4A</figref>.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention provide a number of advances over known transition-to-turbine seals, providing enhanced durability by reducing transition metal temperatures and lowering wear rates of adjacent components such as the transition outlet flange. The inventors have developed a transition-to-turbine seal that takes into account pressure impacts of the more downstream row <b>1</b> vanes, in particular that a bow wake from the vanes may provide a slight but significant higher pressure region adjacent to an upstream gap between a flange of a transition and the seal. Appreciating that this could result in a circumferential deflection of cooling fluid flows from the seal through the gap, the inventors obviated such possible impacts in embodiments of the present invention, and thereby advanced the art.

More particularly, embodiments of the present invention comprise a transition-to-turbine seal that comprises a means for keeping a cooling fluid flow in a substantially radial direction after it emanates from the seal, into the gap, and then travels in the gap toward the hot gas path. One disclosed embodiment provides a plurality of flow partitions along a seal wall designed to partially engage the first flange, wherein the flow partitions comprise a plurality of spaced apart recesses, separated by intervening walls, with each recess comprising one or more cooling apertures, so that the presence of the partitions more clearly assures that respective flows will be directed along the entire inside edge of the gap (i.e., in the hot gas path). Such embodiment, and the invention in general, provide a seal that is multi-purpose: it not only achieves a primary sealing function, but it also cools the transition outlet flange and more uniformly purges hot gases from the gap. The cooling of the flange includes both impingement type and convective type cooling, and the flow further provides uniform gap purging and film cooling. The seal achieves these purposes while providing a robust mechanical junction between the seal and the transition outlet flange, this being due in part to the intervening walls that distribute wear load while still providing for unobstructed outflow of cooling fluids from the cooling apertures in the recesses. As a result of reducing the transition outlet flange and seal metal temperatures, a lower wear at this interface is expected. Additionally, the intervening walls will prevent the recesses to collapse from the mechanical and thermal loads imposed on the seal.

Prior to discussion of an exemplary embodiment, a discussion is provided of a common arrangement of elements of a prior art gas turbine engine. <figref idrefs="DRAWINGS">FIG. 1</figref> provides a schematic cross-sectional depiction of a prior art gas turbine engine <b>100</b> such as may comprise various embodiments of the present invention. The gas turbine engine <b>100</b> comprises a compressor <b>102</b>, a combustor <b>107</b> and combustion chamber <b>108</b> (such as a can-annular type), and a turbine <b>110</b>. During operation, in axial flow series, compressor <b>102</b> takes in air and provides compressed air to a diffuser <b>104</b>, which passes the compressed air to a plenum <b>106</b> through which the compressed air passes to the combustor <b>107</b>, which mixes the compressed air with fuel (not shown), and provides combusted gases via a transition <b>114</b> to the turbine <b>110</b>, which may generate electricity. A shaft <b>112</b> is shown connecting the turbine to drive the compressor <b>102</b>. Although depicted schematically as a single longitudinal channel, the diffuser <b>104</b> extends annularly about the shaft <b>112</b> in typical gas turbine engines, as does the plenum <b>106</b>. Air from the compressor <b>102</b> also travels to the turbine <b>110</b> by various channels (not shown in <figref idrefs="DRAWINGS">FIG. 1</figref>) to provide higher pressure air that surrounds and may enter the hot gas path as it passes through the turbine <b>110</b>. A junction between the transition <b>114</b> and the turbine <b>110</b> is indicated by <b>115</b>, and is the subject of further discussion herein.

Further to conventional aspects of seals provided at such junction <b>115</b> of <figref idrefs="DRAWINGS">FIG. 1</figref>, <figref idrefs="DRAWINGS">FIG. 2</figref> provides a cross-sectional view of the junction of a transition <b>114</b> (only downstream end shown) with a front end of a turbine <b>110</b> (only upstream end shown). <figref idrefs="DRAWINGS">FIG. 2</figref> depicts prior art inner and outer seals <b>120</b> and <b>122</b> for joining an exit flange <b>116</b> (alternatively referred to as an exit rail) of transition <b>114</b> to a front end <b>132</b> of a row <b>1</b> vane segment <b>130</b>. The row <b>1</b> vane segment <b>130</b> comprises a single airfoil <b>134</b> (alternatively referred to as a vane) and is supported along an inner wall <b>136</b> by an inner vane attachment structure <b>140</b> and at a downstream outer end by an outer vane attachment structure <b>142</b> that connects to a row <b>1</b> turbine blade ring <b>144</b>. At each of the forward inner and outer ends the row <b>1</b> vane segment <b>130</b> comprises a respective upstream lip <b>138</b> and <b>139</b> that engages a downstream groove <b>121</b> and <b>123</b> in the respective inner and outer mouth seals <b>120</b> and <b>122</b>. These components surround and define a hot gas path <b>170</b> through which combustion gases pass further into the turbine <b>110</b> of <figref idrefs="DRAWINGS">FIG. 1</figref>.

<figref idrefs="DRAWINGS">FIGS. 3A-3C</figref> provide views of one exemplary embodiment of the present invention. <figref idrefs="DRAWINGS">FIG. 3A</figref> provides a perspective view, from an upstream point of view, of a seal <b>320</b> such as may be utilized along an inner junction between a transition and a row <b>1</b> vane segment of a turbine. Such seal <b>320</b> may be used to replace the seal <b>120</b> depicted in <figref idrefs="DRAWINGS">FIG. 2</figref>. Seal <b>320</b> comprises an upstream portion <b>322</b> that is adapted to receive a transition outlet flange, such as flange <b>116</b> of <figref idrefs="DRAWINGS">FIG. 2</figref>. More particularly, the upstream portion <b>322</b> is generally U-shaped in cross-section and defines a groove <b>335</b> that receives the noted flange. Upstream portion <b>322</b> comprises a primary wall <b>324</b>, features of which are now described. The primary wall <b>324</b> comprises a proximal section <b>325</b> and a distal section <b>326</b>. The proximal section <b>325</b> comprises a plurality of recesses <b>327</b> which are spaced apart and separated by intervening walls <b>328</b>. Each recess communicates with one or more outlets <b>329</b> of cooling fluid holes (see <figref idrefs="DRAWINGS">FIG. 3C</figref> for view of entire cooling fluid hole). The outlets <b>329</b> communicate via the cooling fluid holes with a supply of compressed cooling fluid, such as compressed air that is provided from the compressor (not shown), and the outlets <b>329</b> release this into the respective recesses <b>327</b>. The source of compressed fluid is described in more detail in the discussion regarding <figref idrefs="DRAWINGS">FIG. 3C</figref>. The seal <b>320</b> also comprises downstream portion <b>330</b> downstream of the primary wall <b>324</b> and comprising a groove <b>331</b> which is adapted to engage a lip (not shown) of a row <b>1</b> vane segment (not shown, see <figref idrefs="DRAWINGS">FIG. 2</figref>). A generally planar exposed surface <b>332</b> comprises surfaces of the upstream portion <b>322</b> and the downstream portion <b>330</b> that are oriented to the hot gas path and is the surface of the seal <b>320</b> that is directly exposed in the hot gas path (see <figref idrefs="DRAWINGS">FIG. 2</figref>). As is generally known in the art, this exposed surface <b>332</b> may comprise a number of cooling fluid hole outlets, scoops, and the like, some of which are discussed in regard to <figref idrefs="DRAWINGS">FIG. 3C</figref>. In various embodiments this exposed surface <b>332</b> also may be coated with a thermal barrier coating (TBC).

<figref idrefs="DRAWINGS">FIG. 3B</figref> provides a frontal view from an upstream point of view of a section indicated by the circled area in <figref idrefs="DRAWINGS">FIG. 3A</figref>. <figref idrefs="DRAWINGS">FIG. 3B</figref> more clearly shows the arrangement of the outlets <b>329</b>. For each recess <b>327</b>, the arrangement of two of the three outlets <b>329</b> closer to the hot gas path <b>170</b>, and one of the three outlets <b>329</b> disposed more distally from the hot gas path <b>170</b> and more centrally within the recess <b>327</b>, provides a higher volume of flow closer to the hot gas path <b>170</b> and a graduated increasing flow rate from the more distal to the more proximal areas of the respective recess <b>327</b>. This staggered arrangement of the outlets <b>329</b> provides a relatively effective cooling flow pattern given the primary heat source is the hot gas path <b>170</b>. Notwithstanding this approach, although depicted to provide three outlets <b>329</b> arranged in triangular orientation to one another, this is not meant to be limiting, and other staggered arrangements are within the scope of the claims. Staggered hole arrangements are also preferred for structural reasons, principally to disrupt stress patterns leading to fatigue cracks.

Also, notwithstanding the above specific embodiment, any number of outlets of cooling fluid holes may be provided in each of the recesses. Further, it is noted that the diameter of the cooling fluid holes may be increased relative to other holes and other recesses for the recesses that are positioned upstream of an airfoil of the adjacent row <b>1</b> vane segment, which therefore may be affected by a bow wake of the airfoil during operation. For example, if an airfoil as indicated by bold arrow <b>334</b> is directly downstream of the recess identified as <b>327</b>-B, then a bow wake may present a higher pressure at the opening of the recesses <b>327</b>-A, <b>327</b>-B, and <b>327</b>-C into hot gas path <b>170</b>. In such case, to at least partially compensate for this, the cooling fluid holes for recesses <b>327</b>-A, <b>327</b>-B, and <b>327</b>-C may be provided with larger diameters (example shown as dashed circles) than the other recesses <b>327</b> depicted in <figref idrefs="DRAWINGS">FIG. 3B</figref>. Alternatively, or in combination with the relatively larger cooling fluid holes, more holes may be provided in the recesses upstream of such airfoil than the other recesses <b>327</b> depicted in <figref idrefs="DRAWINGS">FIG. 3B</figref>.

<figref idrefs="DRAWINGS">FIG. 3B</figref> also shows additional cooling fluid hole outlets <b>333</b> arranged on surface <b>332</b>. These may be provided in a quantity and having diameters that may be affected by the flow coming from outlets <b>329</b> of recesses <b>327</b>. That is, the number and flow of cooling fluid from theses apertures <b>333</b> may be less than in conventional seals owing to the increased flow from the outlets <b>329</b> from recesses <b>327</b> in the present embodiment. In various embodiments the cooling fluid holes leading to outlets <b>329</b> may be of a diameter between 1.5 mm and 2.0 mm. Further, in the embodiment as depicted in <figref idrefs="DRAWINGS">FIG. 3B</figref>, the distal surfaces <b>337</b> of intervening walls <b>328</b> are coplanar with the engaging surface <b>338</b> of distal section <b>326</b> of primary wall <b>324</b>. This provides for more uniform load bearing against the flange (not shown, see <figref idrefs="DRAWINGS">FIG. 3C</figref>) of the transition that fits into the groove defined by upstream portion <b>322</b>. This exemplary coplanar arrangement, while not meant to be limiting, provides for an increased mechanical robustness of the seal <b>320</b>.

Also shown in <figref idrefs="DRAWINGS">FIG. 3B</figref> is a slot <b>340</b> that is designed to receive the shaft of a pin (not shown) that is fit into the transition outlet flange (see <figref idrefs="DRAWINGS">FIG. 2</figref>). This is done to provide a “safety stop” to prevent circumferential rotation of the seal <b>320</b> during operation.

<figref idrefs="DRAWINGS">FIG. 3C</figref> is a schematic representation of seal <b>320</b> taken along line <b>3</b>C-<b>3</b>C of <figref idrefs="DRAWINGS">FIG. 3B</figref>, and also includes a cross-sectional schematic representation of a downstream end <b>400</b> of a transition, including transition outlet flange <b>416</b>. In <figref idrefs="DRAWINGS">FIG. 3C</figref> is shown, along the exposed surface of primary wall <b>324</b>, a primary wall radial seal length <b>323</b> that may be defined as the radial exposed distance that may be contacted by a flange that enters the groove <b>335</b>. It is noted that since the line <b>3</b>C-<b>3</b>C is not taken along an intervening wall, the identified intervening wall <b>328</b> is in the background, and a gap <b>401</b> is identified (between downstream surface <b>417</b> and the proximal section <b>325</b>), a part of which occupies the recess <b>327</b>. This gap <b>401</b> is highly subdivided compared with gaps of prior art embodiments that lack the intervening walls. More clearly viewable in <figref idrefs="DRAWINGS">FIG. 3C</figref> is the groove <b>335</b> as formed within the upstream portion <b>322</b>, which receives flange <b>416</b>. Also, a cooling fluid hole <b>339</b> in the plane of the section is shown in side view (with dashed lines representing another cooling fluid hole not in the plane of the section). As discussed above in reference to <figref idrefs="DRAWINGS">FIG. 3A</figref>, the cooling fluid holes <b>339</b> communicate between their outlets <b>329</b> and a supply of compressed cooling fluid. This supply of compressed fluid is provided via void <b>360</b>, which is in fluid communication with the compressor (see <figref idrefs="DRAWINGS">FIG. 1</figref>) and supplies compressed fluid at a higher pressure than the pressure of gases in the hot gas path <b>170</b>. Cooling fluid, such as compressed air, also flows from void <b>360</b> into cooling fluid holes <b>333</b> to direct cooling fluid directly into the gas path <b>170</b>. An optional impingement plate <b>342</b> is shown; this provides impingement cooling to an underside surface <b>343</b> of a first region <b>344</b> of downstream portion <b>330</b>. It is noted that first region <b>344</b> is optional and it is recognized that in some embodiments the latter may be reduced or eliminated, with appropriate design modifications to, or elimination of, the optional impingement plate <b>342</b> and/or cooling fluid holes <b>333</b>.

Further to the cooling characteristics of cooling fluid holes <b>339</b>, by viewing <figref idrefs="DRAWINGS">FIG. 3C</figref> it is clear that these cooling fluid holes <b>339</b> provide an enhanced cooling to a downstream surface <b>417</b> of transition outlet flange <b>416</b>. This provides better cooling to the flange <b>416</b>, which will result in less thermal degradation and increased component life. This enhanced cooling is in part due to the outlets <b>329</b> being positioned to direct cooling fluid lower (more distal from the hot gas path <b>170</b>) along downstream surface <b>417</b>, that is, more radially outward from hot gas path <b>170</b>. In various embodiments, the outlets <b>329</b> are positioned such that at least thirty percent (30%) of the radial seal length <b>323</b> receives cooling fluid flowing from the outlets <b>329</b>. More particularly, in some embodiments the outlets <b>329</b> are positioned more radially remote from the exposed surface <b>332</b> and the hot gas path <b>170</b> such that at least seventy percent (70%) of the radial seal length <b>323</b> receives cooling fluid flowing from the outlets <b>329</b>. Also, it is appreciated that in various embodiments, the outlets <b>329</b> are positioned such that between about thirty percent (30%) and about seventy percent (70%) of the radial seal length <b>323</b> of the primary wall <b>324</b> receives cooling fluid flowing from the outlets <b>329</b>. This range is not meant to be limiting, and all sub-ranges therein are included in the scope of the invention. It is noted that by positioning the outlets <b>329</b> more radially outward from the exposed surface <b>332</b> and the hot gas path <b>170</b>, the embodiment may more effectively achieve the functionality of cooling the transition outlet flange <b>416</b> (and consequently achieve the desired lower thermal degradation, lowered wear and longer component life). From a design standpoint, this is balanced with the objective of structural robustness.

Also, the cooling effect provided by such flow is a combination of impingement cooling and convective cooling, and this flow contrasts with expected low flow such as through the groove <b>335</b> which is restricted by the close proximity between the distal section <b>326</b> and a directly opposing distal section of the transition outlet flange downstream surface <b>417</b>. Thus, the flow from the outlets <b>329</b> into a respective recess <b>327</b> provides a flow having an established flow velocity effective to provide a desired cooling greater than the expected flow rate through a relatively stagnant area bounded in part by the distal section <b>326</b> where the flow is directed toward the hot gas path <b>170</b> and establishes a film cooling flow across the exposed surface <b>332</b>. Further, in various embodiments the respective outlets <b>329</b> provides a selected flow of cooling fluid into the recesses <b>327</b> that is effective to purge the gap <b>401</b> between the transition outlet flange <b>416</b> and the seal <b>320</b>. This purging reduces the likelihood of hot gas ingestion due to a maintenance of recess-to-hot gas path local pressure gradients.

This approach contrasts with other approaches known in the art. Also, outlets such as these may be designed to be effective to provide an impingement cooling and a convective cooling of the transition outlet flange.

It is recognized that impingement cooling is achieved when a flow of sufficient force, directed toward a surface, is effective to disturb a thermal gradient over that surface. This increases the thermal transfer from the surface. In addition to impingement and convection cooling of the downstream surface <b>417</b> (which results in the overall flange <b>416</b> remaining cooler), the flow of cooling fluids out of the gap <b>401</b> and into the hot gas path <b>170</b> purges the gap <b>401</b>, reducing or eliminating hot gas ingestion due to maintenance of desired local recess-to-hot gas path pressure gradients, and also provides a film cooling effect across the exposed surface <b>332</b>. The partitioning of the gap <b>401</b> into a plurality of recesses <b>327</b> better assures the latter two functions.

The overall design, combining the noted features and relationships, provides beneficial cooling of both the transition outlet flange and the seal itself.

<figref idrefs="DRAWINGS">FIGS. 4A and 4B</figref> show one approach, not meant to be limiting, of reducing undesired leakage of cooling fluid where adjacent transition-to-turbine seals join. <figref idrefs="DRAWINGS">FIG. 4A</figref> provides an end perspective view of a seal <b>420</b> (shown only partially) in accordance with the present invention, showing a female ship lap <b>452</b> at the lateral end. <figref idrefs="DRAWINGS">FIG. 4B</figref> provides an end perspective view of an adjacent seal <b>421</b> (shown only partially) in accordance with the present invention, showing a male ship lap <b>454</b> at the lateral end for mating engagement with the female ship lap <b>452</b> shown in <figref idrefs="DRAWINGS">FIG. 4A</figref>. Joining of adjacent seals <b>420</b> and <b>421</b> comprising overlapping and mating lap joints <b>452</b> and <b>454</b> reduce leakage through the junctions of such components. Joints such as these are effective to reduce overall air flow leakage into the hot air bulk stream and accordingly improve seal performance characteristics.

Also, the term “means for sealingly engaging a transition outlet flange” is taken to include all of the above structural elements of embodiments for effectuating a sealing engagement between the transition-to-turbine seal, of which this means is a portion, and a transition outlet flange. Also, it is recognized that various specific design modifications may be effectuated without departing from the scope of such means. For example, a complete U-shaped design need not be employed for a design of a means for sealingly engaging a transition outlet flange. The “means for directing cooling fluid flows” is taken to include the various depicted embodiments of pluralities of recesses comprising cooling fluid holes with outlets in respective recesses, or analogous defined partitioned areas, each separated by intervening wall structures. More particularly, “means for conveying a respective cooling fluid flow” is taken to include the various depicted embodiments, and variations based on design modifications, of one or more cooling fluid holes in a particular recess or analogous defined partition area. Similarly, “means for restricting” is taken to include the intervening wall structures and analogous structures. A “means for portioning” is taken to include any approach to provide a relatively greater flow to particular regions along a transition-to-turbine seal at the junction of the transition, such as for balancing overall flows given greater back pressures upstream of a turbine row <b>1</b> airfoil. Examples include, but are not limited to: greater diameter cooling fluid holes in such upstream areas relative to other areas; more cooling fluid holes in such upstream areas; and combinations thereof.

Also, a “a means for sealingly engaging an adjacent turbine component” is taken to include all of the above structural elements of embodiments for effectuating a sealing engagement between the transition-to-turbine seal, of which this means is a portion, and an adjacent transition component such as the lip of a row <b>1</b> vane segment, and various specific design modifications.

Having thusly described aspects and features of particular embodiments, it is appreciated that the invention relates not only to the transition-to-turbine seal apparatuses, such as those described and illustrated, but also to transition-to-turbine seal junctions comprising the transition-to-turbine seals of the present invention, and to gas turbine engines comprising the seals and the transition-to-turbine seal junctions of the present invention.

All patents, patent applications, patent publications, and other publications referenced herein are hereby incorporated by reference in this application in order to more fully describe the state of the art to which the present invention pertains, to provide such teachings as are generally known to those skilled in the art.

While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Moreover, when any range is described herein, unless clearly stated otherwise, that range includes all values therein and all sub-ranges therein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.